Centered near the Williamette Falls and Clackamas Rapids along the Columbia River, the Clackamas numbered about 1,800 when Lewis and Clark encountered them in 1805. Their name was also the name of the dialect of Chinook that they spoke.

The Clackamas lived in the cedar-plank houses common to the area and traded with Indian neighbors and the white men who passed by.

Like other Chinook-related bands, the Clackamas practiced head-flattening. From infancy the head is compressed between boards, sloping the forehead backward.

By 1851, only 88 members of the tribe remained. Today the Clackamas live on the Grande Ronde Reservation in Oregon.